JPH01280723A - Liquid crystal element - Google Patents

Abstract

PURPOSE:To improve the orienting property of liquid crystal, especially, ferroelectric liquid crystal so as to obtain a liquid crystal element which shows an oriented property of a uniform mono-domain state and, at the same time, does not decline in contrast and has an excellent bi-stability by using specific oriented films. CONSTITUTION:An upper and lower substrates 2 are provided in a facing state between polarizing plates 1 and 1, with their outer peripheral sections being sealed with a sealing agent 5, and ferroelectric liquid crystal 6 is enclosed in the space formed by the substrates 2 and sealing agent 5. Transparent electrodes 3 are provided on the surfaces of the substrates 2 and oriented films 4 are formed on the facing surfaces of the substrates 2. A polymeric compound for liquid crystal whose temperature at which the compound shows a liquid crystal state is higher than the temperature at which the ferroelectric liquid crystal 6 transforms to a isotropic phase is used for the oriented films 4. It is preferable to use a polymeric compound, such as polyacrylate, polysiloxane, etc., which has a mesogen group in the principal or side chain and shows a nematic or smectic phase in a liquid crystal state for the polymeric compound having the liquid crystal property.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a liquid crystal element that has uses such as display elements, light valves, optical shutters, and optical memories.

[Prior art]

Liquid crystal display elements using ferroelectric liquid crystals, liquid crystal shutters,
In liquid crystal elements such as liquid crystal light valves, switching elements for optical information processing, and optical memories, it is necessary to preferentially align liquid crystal in one direction. Since this alignment treatment has a great influence on the quality of these liquid crystal elements, much research has been conducted on it.

The alignment state of liquid crystal on the substrate surface can be broadly classified into homogeneous alignment, which is aligned parallel to the substrate surface, and homeotropic alignment, which is aligned perpendicular to the substrate surface.

In actual liquid crystals, by applying an electric field etc. to the ferroelectric liquid crystals oriented in this way, the alignment state of the liquid crystals is changed, and by using birefringence, dichroism, etc., light is turned on and off. conduct.

Conventional methods for aligning liquid crystals include oblique vapor deposition of inorganic materials, rubbing of silane coupling agent coatings, and rubbing of organic polymer coatings, but none of these methods are satisfactory. Oblique deposition of inorganic materials is a batch process, which takes time.
Poor productivity. Moreover, the method of rubbing the coating film of the silane coupling agent is poor in reliability. Furthermore, in the method of rubbing an organic polymer coating film to form an alignment film, many of the films generally have poor heat resistance. In the case of polyimide, which has good heat resistance and is widely used, it is difficult to obtain homogeneous monodomains, the contrast ratio during driving is low, and furthermore, it has poor bistability and high-speed response. The problem is that the value decreases.

Furthermore, conventionally known ferroelectric liquid crystals generally have a disadvantage that they have poor mechanical strength and break when subjected to impact force.

〔the purpose〕

The present invention improves the alignment of liquid crystals, particularly ferroelectric liquid crystals, by using a specific alignment film, exhibits uniform monodomain alignment, and has a large contrast ratio of 1 to 1 during driving, resulting in good results. An object of the present invention is to provide a liquid crystal element that has bistability and excellent mechanical strength.

〔composition〕

According to the present invention, in a liquid crystal element which has an electrode and an alignment layer for aligning liquid crystal on the inside of a pair of opposing substrates, and a ferroelectric liquid crystal layer is provided between them, the component forming the alignment layer is A liquid crystal element is provided, which uses a liquid crystalline polymer compound whose temperature at which it exhibits a liquid crystal state is higher than the temperature at which a bipedal ferroelectric liquid crystal transitions to an isotonic phase.

Generally, the alignment of liquid crystals is carried out by the alignment regulating force of an alignment film, but if this alignment regulating force is too strong, it inhibits the bistability, which is one of the characteristics of ferroelectric liquid crystals, leading to a decrease in high-speed response.

The present inventors have discovered that even if a ferroelectric liquid crystal is used as the liquid crystal, it is possible to obtain uniform monodomain alignment with few defects, have excellent mechanical strength, and exhibit stable bistability during driving. As a result of research into liquid crystal elements with a large contrast ratio, we have discovered a liquid crystal element using a liquid crystalline polymer compound whose temperature at which it exhibits a liquid crystal state as an alignment film is higher than the temperature at which ferroelectric liquid crystal transitions to an isokinetic phase. ”-Note 1■1
The present invention was completed based on the discovery that these conditions are consistent with each other.

Therefore, the liquid crystal element of the present invention is characterized in that a liquid crystalline polymer compound whose temperature at which it exhibits a liquid crystal state is higher than the temperature at which ferroelectric liquid crystal transitions to an isotropic phase is used as the main component of the alignment film.

There are various kinds of polymer compounds having such liquid crystal properties, but in particular, polymer compounds having a mesogenic group in the main chain or side chain and exhibiting a nematic phase or a smectic phase in the liquid crystal state, such as (polyacrylate-1 and polyacrylate-1), The use of polymeric compounds such as siloxane) is preferred.

The representative side is shown below.

[Example of main chain type nematic liquid crystalline polymer compound] [Example of side chain type nematic liquid crystalline polymer compound] [Example of main chain type smectic liquid crystalline polymer compound] [Side chain type smectic liquid crystalline polymer compound] Example of polymer compound] To form an alignment film on a substrate using the alignment film material of the present invention, the liquid crystalline polymer compound is vapor-deposited, spin coat 1 to roller coat 1
~, applied by a conventionally known method such as spray coating or dipping, and then heated to remove the solvent to form an alignment film with a film thickness of 100 to 5,000 layers, preferably 500 to 2,000 layers. Flocked fabric 4 Relabinc treatment or oblique vapor deposition may be performed using a polyester flocked fabric or the like.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an example of the structure of a liquid crystal element according to the present invention. An upper substrate 2 and a lower substrate 2 are disposed facing each other between polarizing plates 1, 1, their outer peripheries are sealed with a sealant 5, and a ferroelectric liquid crystal 6 is sealed inside.

As the liquid crystal, a ferroelectric liquid crystal mixed with a dichroic dye can also be used. A transparent electrode 3 is provided on the surface of the lower substrate 2, and an alignment film 4 is further formed on the upper surface 2 of the lower substrate. Further, a transparent electrode 3 is provided on the opposing surfaces of the two substrates 1, and an alignment film 4 is further formed below the transparent electrode 3.

The alignment films 4, 4 are made of the liquid crystalline polymer compound, and the liquid crystal molecules are aligned in the horizontal direction with respect to the alignment films 4, 4.

FIG. 2 shows a configuration example of another embodiment of the present invention.

In this embodiment, a base layer 8 made of an organic polymer film is first formed on the surface of the substrate and/or the lower substrate 2, and an alignment film 4 made of a liquid crystal polymer compound is formed thereon. The base layer 8 made of an organic polymer film is formed of a thin film of a polymer compound such as polyimide, polyamide, polyvinyl alcohol, polyacryloni-1-lyl, or a silane coupling agent, and is subjected to a rubbing treatment if necessary. This is what I did. By forming such a base layer 8, the orientation of the alignment film 4 itself is improved, and furthermore, the orientation of the ferroelectric liquid crystal 6 is improved.

In the liquid crystal element thus formed, the liquid crystal molecules can be uniaxially aligned by a conventionally known uniaxial alignment treatment such as rubbing treatment or oblique evaporation treatment. Further, although this -axis alignment treatment may be performed on both of the alignment films 4, 4, in some cases, better results may be obtained when it is performed on only one of them.

The substrate used in the present invention has a patterned transparent electrode on its surface, and conventionally known substrates are used, such as glass, polyester such as polyethylene terephthalate, polybutylene terephthalate, etc. Epoxy resin, phenolic resin, polyimide, polycarbonate 1-
, polysulfone, polyether sulfone, polyetherimide, acetylcellulose, polyamino acid ester,
Made from heat-resistant resins such as aromatic polyamides, vinyl polymers such as polystyrene, polyacrylic esters, polymethacrylic esters, polyacrylamide, polyethylene, and polypropylene, fluorine-containing resins such as polyvinylidene fluoride, and modified products thereof. Examples include plastic films made of plastic.

Further, as the liquid crystal, a conventionally known ferroelectric liquid crystal material may be optionally used. A specific example is shown below.

[Ship base-based ferroelectric liquid crystal with amyl alcohol as an asymmetric source] [Ferroelectric liquid crystal with a hydroxyl group at the ortho position of the Schiff base] [Ship base-based ferroelectric liquid crystal with a halogen or cyano group at the asymmetric carbon ]C, o2n+, 0-1O-C
I(=:N0CH-cH-cOo-C1(2-68-C
I+3r+=-4,5-8,10 [Other Schiff base compounds] [Azo and azoxy ferroelectric liquid crystal] Cl1H211
+l O−c>N=N−O)−()−C1,−C;1toQHs n=16 [Bicyclic ferroelectric liquid crystal] H3 1011) 1. at(co,)2 [Polycyclic ferroelectric liquid crystal using amyl alcohol as an asymmetric source] [Ferroelectric liquid crystal with a ring substituent such as halogen or cyano group introduced] [Ferroelectric liquid crystal with a pyrimidine ring Liquid crystal] [Ferroelectric liquid crystal using amino acids as an asymmetric source] c, u2n,, a
-o-(Q)-(Q16-o-co, -4n-cH:+
+3), n=8-12 [Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 A 3% by weight tetrahydrofuran solution of nematic liquid crystalline polysiloxane (n=46) represented by the general formula Cm) was applied onto a glass substrate by spin coating to obtain an alignment film with a thickness of 1.00 OA. . After rubbing the surface of the alignment film with a rayon flocked cloth, the films were bonded together with spacer particles having a particle size of 2.0 μm interposed therebetween to produce a cell. C5-1013 manufactured by Chisso Corporation was injected into this as a ferroelectric liquid crystal, and its orientation was examined. It was found to be extremely good, and no deterioration was observed even after being left for a long period of time.

Example 2 Polyimide solution JI manufactured by Japan Synthetic Rubber was placed on a glass substrate.
B-1 was applied by spin coating to a thickness of approximately 50 mm.
A polyimide base layer of 0 was formed. After rubbing this surface with a rayon flocked cloth, the nematic liquid crystalline polysiloxane represented by the general formula [V] (n=46
A 3% by weight toluene solution of 1.) was applied thereon by spin coating as well. ．． 00
An alignment film was formed for 0 people. Next, the substrate was heated to about 270° C. and slowly cooled to 240° C. at a rate of 1° C./min to orient the alignment film itself, and then rapidly cooled to room temperature to fix that state. Thereafter, as in Example 1, a cell was fabricated by bonding them together via spacer particles with a particle size of 2.0 μm, and DOBAMBC (decyloxybenzylidene aminomethyl butyl cinnamate) was injected as a ferroelectric liquid crystal to improve the orientation. Upon examination, it was found to be in very good condition, and no disturbance in orientation occurred even when impact force was applied.

Example 3 3% by weight of smectic liquid crystalline polysiloxane (n=46) represented by the above general formula [■] on a glass substrate
A tetrahydrofuran solution was applied by spin coating to a thickness of about 1. ．． 000 alignment films were obtained. After rubbing the surface of the alignment film with rayon flocked cloth, the particle size was 2.0.
A cell was fabricated by bonding them together via μm spacer particles. Among these are C3-1 manufactured by Chisso Corporation as a ferroelectric liquid crystal.
01,] was injected and the orientation was examined, and it was found to be extremely good, and no deterioration was observed even after being left for a long period of time.

Example 4 Polyimide solution J manufactured by Nippon Synthetic Rubber ■ was placed on a glass substrate.
IB-1 was applied by spin coating to a thickness of 50
A polyimide base layer of 0 was formed. After the surface was rubbed with rayon flocked cloth, a 3% by weight tetrahydrofuran solution of smectic liquid crystal polysiloxane (n=46) represented by the general formula [■] was applied thereon by spin coating, and the coating was applied with a coating of approximately 1,000% by weight. A human alignment film was formed. Next, heat the substrate to approximately 1.80°C and
After slowly cooling to 140°C at a rate of 140°C/min to orient the alignment film itself, it was rapidly cooled to room temperature and fixed in that state. In the same manner as in Example 1, a cell was fabricated by pasting spacer particles with a particle size of 2 Opm, and C3-]013 manufactured by Chisso Corporation was injected as a ferroelectric liquid crystal, and the orientation was examined and found to be extremely good. And from the outside? Even when AF impact force was applied, the orientation was hardly disturbed.

〔effect〕

Since the liquid crystal element of the present invention uses a specific alignment film,
The alignment of liquid crystals, especially ferroelectric liquid crystals, has been improved, showing a uniform monodomain state alignment and a concentric 1-
It has excellent high-speed response without any deterioration in performance, and also has excellent mechanical strength.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing an example of the structure of a liquid crystal element of the present invention using a ferroelectric liquid crystal. ]...Polarizing plate, 2.Substrate, 3.Transparent electrode, 4.
alignment film, 5... sealing agent, 6... ferroelectric liquid crystal layer, 7
Spacer, 8... Base layer.

Claims (2)

[Claims] (1) In a liquid crystal element that has an electrode and an alignment layer for aligning liquid crystal on the inside of a pair of opposing substrates, and a ferroelectric liquid crystal layer is provided between them, the component forming the alignment layer is in a liquid crystal state. 1. A liquid crystal element using a liquid crystalline polymer compound which exhibits a temperature higher than a temperature at which the ferroelectric liquid crystal transitions to an isotropic phase. (2) The liquid crystal element according to claim 1, wherein a base layer made of a polymer compound is provided inside the substrate.